Surgical stapling apparatus with firing lockout mechanism

ABSTRACT

A surgical stapling apparatus is provided which includes a first jaw supporting an anvil assembly and a second jaw supporting a cartridge assembly. The cartridge assembly supports a firing lockout assembly which includes a latch member having a blocking member. The latch member is movable between a first position and a second position. In the first position, the blocking member of the latch member is aligned with the stop surface of the drive member to prevent advancement of the drive member within the tool assembly and in the second position, the blocking member is misaligned with the stop surface of the drive member to permit advancement of the drive member within the tool assembly. A biasing member is positioned to urge the latch member towards the first position. In the retracted position of the drive member, the latch member is in the first position.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. application Ser. No.15/690,620, filed Aug. 30, 2017 which is a Continuation of U.S.application Ser. No. 14/230,516, filed on Mar. 31, 2014, now U.S. Pat.No. 9,757,126. Each of these disclosures is incorporated by referenceherein in its entirety.

1. TECHNICAL FIELD

The present disclosure relates to surgical stapling apparatus. Moreparticularly, the present disclosure relates to surgical staplingapparatus having a firing lockout mechanism.

2. BACKGROUND

Surgical stapling apparatus for stapling tissue are well known in theart and typically include a handle assembly, a body portion extendingdistally from the handle assembly, and a tool assembly supported on thedistal end of the body portion. The tool assembly includes first andsecond jaws which are movable in relation to each other betweenunapproximated and approximated positions. The first jaw supports ananvil assembly and the second jaw supports a cartridge assembly whichhouses a plurality of staples. The cartridge can also include a knifefor severing tissue. In known apparatus, a fired or spent cartridge canbe replaced with an unfired or fresh cartridge to facilitate reuse ofthe surgical stapling apparatus.

In order to prevent refiring of the surgical stapling apparatus with aspent cartridge, or to prevent firing of a surgical stapling apparatuswhich does not include a cartridge, it is known to provide a lockoutmechanism which prevents advancement of a drive member of the staplingapparatus. Although known lockout mechanisms are effective to preventfiring of a surgical stapling apparatus which includes a spent cartridgeor does not include a cartridge, an improved, reliable lockout mechanismis desired.

SUMMARY

A surgical stapling apparatus provided in accordance with the presentdisclosure includes a body portion defining a longitudinal axis having aproximal end and a distal end, and a tool assembly supported on thedistal end of the body portion. The tool assembly includes an anvilassembly and a cartridge assembly and is movable from an unapproximatedposition to an approximated position. A drive member is movablysupported within the tool assembly from a retracted position to anadvanced position to move the tool assembly from the unapproximatedposition to the approximated position. The drive member has a stopsurface. A firing lockout assembly includes a latch member having ablocking member and a biasing member. The latch member is pivotallysupported within the tool assembly and movable from a first position toa second position, wherein in the first position the blocking member ofthe latch member is aligned with the stop surface of the drive member toprevent advancement of the drive member within the tool assembly and inthe second position the blocking member is misaligned with the stopsurface of the drive member to permit advancement of the drive memberwithin the tool assembly. The biasing member is positioned to urge thelatch member towards the first position such that in the retractedposition of the drive member, the latch member is in the first position.

In embodiments, the cartridge assembly includes an actuation sledpositioned within the tool assembly to be engaged by the drive member asthe drive member is moved from the retracted position towards theadvanced position. The drive member effects movement of the actuationsled from a retracted position to an advanced position upon movement ofthe drive member from the retracted position to the advanced position.

In embodiments, the actuation sled is configured to engage the latchmember to move the latch member from the first position to the secondposition when the actuation sled is advanced distally within thecartridge assembly by the drive member.

In embodiments, the latch member includes a u-shaped body including abase member which supports the blocking member and a pair of spaced legsextending distally from the base member. Each of the spaced legssupports a centrally located pivot member and has a distal projection.

In embodiments, the actuation sled includes at least one proximal fingerwhich is positioned to engage one of the distal projections of the pairof spaced legs of the latch member as the actuation sled is moveddistally within the cartridge assembly to effect movement of the latchmember from the first position to the second position.

In embodiments, the at least one proximal finger includes two proximalfingers, each of which are positioned to engage a respective one of thedistal projections of the pair of spaced legs of the latch member toeffect movement of the latch member from the first position to thesecond position.

In embodiments, the surgical stapling apparatus includes a mountingassembly including a mounting portion, wherein the mounting portiondefines a pair of hooked arms. Each of the pivot members of the latchmember is supported on a respective one of the pair of hooked arms.

The drive member includes a body and a working end. The working endincludes an upper flange and a lower flange interconnected by a verticalstrut and is positioned to engage the actuation sled to move theactuation sled distally within the cartridge assembly.

In embodiments, the mounting assembly defines a shoulder positioned toengage the blocking member to retain the latch member in the firstposition.

In embodiments, the anvil assembly defines a first cam surface and thecartridge assembly defines a second cam surface and the drive member ismovable from the retracted position to an intermediate position. In theintermediate position, the upper and lower flanges of the working end ofthe drive member engage the first and second cam surfaces to move thetool assembly to the approximated position.

In embodiments, the proximal finger of the actuation sled is engagedwith one of the distal projections of the latch member to retain thelatch member in the second position the intermediate position of thedrive member.

In embodiments, the blocking member of the latch member is positioned toengage a bottom surface of the body of the drive member as the drivemember is moved from the intermediate position towards the advancedposition to retain the latch member in the second position.

In embodiments, the actuation sled is in abutting relationship with theworking end of the drive member such that upon movement of the drivemember from the advanced position back to the retracted position, theactuation sled remains in a distal end of the cartridge assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure are described herein withreference to the drawings, wherein:

FIG. 1 is a side, perspective view of an embodiment of the presentlydisclosed surgical stapling apparatus including a tool assembly in anunapproximated position;

FIG. 1A is a side, perspective view of a disposable reload of thesurgical stapling apparatus shown in FIG. 1;

FIG. 2 is a side, perspective view of the replaceable reload shown inFIG. 1A with parts separated;

FIG. 3 is an enlarged, side perspective view of the indicated area ofdetail shown in FIG. 2;

FIG. 4 is a side perspective view with parts separated of a mountingassembly, lockout mechanism and wedge member positioned adjacent adistal end of a drive member of the surgical stapling apparatus;

FIG. 4A is a top plan view of a latch member.

FIG. 5 is a perspective view from the bottom of the wedge member,lockout mechanism and mounting assembly of the disposable reload shownin FIG. 1A in an assembled state;

FIG. 6 is a side, cross-sectional view of the proximal end of the toolassembly, the mounting assembly, and distal end of the body portion ofthe surgical stapling apparatus shown in FIG. 1 with the tool assemblyin the open position prior to firing of the surgical stapling apparatus;

FIG. 7 is a side, perspective view of a latch member of the lockoutmechanism supported on the mounting assembly adjacent a working end ofthe drive member;

FIG. 7A is a side, cross-sectional view of the proximal end of the toolassembly, the mounting assembly, and the distal end of the proximal bodyportion of the reload of the surgical stapling apparatus shown in FIG. 1with the working end of the drive member advanced to engage the wedgemember;

FIG. 7B is a side, perspective view of the latch member of the lockoutmechanism supported on the mounting assembly adjacent the working memberof the drive member with the working member moved into engagement withthe wedge member in the position shown in the FIG. 7A;

FIG. 8 is a side, cross-sectional view of the proximal end of the toolassembly, the mounting assembly, and the distal end of the proximal bodyportion of the reload of the surgical stapling apparatus shown in FIG. 1with the working member advanced to a position to advance the wedgemember into engagement with the latch member to begin to rotate thelatch member in a clockwise direction to an unlocked position;

FIG. 9 is a side perspective view of the latch member of the lockoutmechanism supported on the working end of the drive member, with partsremoved, in the position shown in FIG. 8;

FIG. 10 is a side, cross-sectional view of the proximal end of the toolassembly, the mounting assembly, and the distal end of the proximal bodyportion of the reload of the surgical stapling apparatus shown in FIG. 1with the working member advanced to a position to advance the wedgemember to support the latch member in the unlocked position;

FIG. 11 is a side, perspective view of the latch member of the lockoutmechanism supported on the mounting assembly adjacent the working end ofthe drive member, with parts removed, in the position shown in FIG. 10;

FIG. 11A is a side, cross-sectional view of the proximal end of the toolassembly, the mounting assembly, and the distal end of the proximal bodyportion of the reload of the surgical stapling apparatus shown in FIG. 1with the working member advanced to a position to advance the wedgemember beyond the latch member such that the latch member is supportedin the unlocked position by the drive member;

FIG. 11B is a side, perspective view of the latch member of the lockoutmechanism supported on the mounting assembly adjacent the working end ofthe drive member, with parts removed, in the position shown in FIG. 11A;

FIG. 12 is a side, cross-sectional view of the proximal end of the toolassembly, the mounting assembly, and the distal end of the proximal bodyportion of the reload of the surgical stapling apparatus shown in FIG. 1with the working end of the drive member retracted and the latch membermoving to the locked position; and

FIG. 13 is a side, perspective view of the latch member of the lockoutmechanism supported on the mounting assembly adjacent the working end ofthe drive member in the locked position shown in FIG. 12.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the presently disclosed surgical stapling apparatusincluding a firing lockout mechanism will now be described in detailwith reference to the drawings wherein like reference numerals designateidentical or corresponding elements in each of the several views. Inthis description, the term “proximal” is generally used to refer to theportion of the apparatus that is closer to a clinician, while the term“distal” is generally used to refer to the portion of the apparatus thatis farther from the clinician.

FIGS. 1 and 1A illustrate an embodiment of the presently disclosedsurgical stapling apparatus shown generally as 100. The surgicalstapling apparatus 100 includes a handle assembly 102, a body portion104, and a tool assembly 106. The handle assembly 102 includes astationary handle 102 a, a movable handle 102 b, a retraction member 107a and an articulation member 107 b. In embodiments, the tool assembly106 forms part of a replaceable reload 108 which also includes aproximal reload body portion 110 which supports the tool assembly 106.The reload 108 will be discussed in further detail below. Alternatively,the tool assembly 106 can be supported directly on the distal end of thebody portion 104.

Referring to FIGS. 1A and 2, the replaceable reload 108 includes thetool assembly 106, the proximal body portion 110, an intermediatemounting assembly 112, a drive member 130 and firing lockout assembly200 which will be described in further detail below. The mountingassembly 112 is secured to the tool assembly 106 and is pivotallycoupled to the proximal body portion 110 of the reload 108 to pivotallysecure the tool assembly 106 to the proximal body portion 110. Thereload 108 is substantially as described in US Publication No.2013/0098965 (“the '965 publication”) except that the firing lockoutmechanism has been changed. US Publication No. 2013/0098965 is herebyincorporated by reference herein in its entirety. Accordingly, thecomponents of the reload 108 which are common to that which is disclosedin the '965 publication will be briefly described herein and the newfiring lockout mechanism 200 and its method of operation will bedescribed in detail herein.

The tool assembly 106 includes an anvil assembly 114 and a cartridgeassembly 116 which are movable in relation to each other betweenunapproximated and approximated positions. The anvil assembly 114includes an anvil body 120 and an anvil plate 122 which is secured tothe underside of the anvil body 120 to define a channel 126 (FIG. 6).The anvil plate 122 defines plurality of staple receiving depressions122 a (FIG. 6) and a longitudinal slot 124 which is dimensioned toslidably receive a portion of the working end 210 of a drive member 130of the disposable reload 108 as will be discussed in further detailbelow. A proximal end of the anvil body 120 includes a bracket 132defining a hole 132 a for receiving a cylindrical pivot member 112 a ofthe mounting assembly 112.

The cartridge assembly 116 includes a support plate 136, cartridge body138, a plurality of staples, and a staple firing assembly that includesa sled 148 and is further discussed below. The cartridge assembly 116 isreceivable in a channel 134 or channel assembly. The cartridge body 138and the support plate 136 are attached to the channel 134 by a snap-fitconnection as described in the '965 publication which has beenincorporated herein by reference. Other forms of connection arecontemplated and can be used in place of a snap-fit, or in additionthereto. The channel 134 or channel assembly is pivotally secured to theanvil body 120 by pivot members 139 which extend through openings 139 aformed in the anvil body 120 and the channel 134. The cartridge body 138defines a plurality of laterally spaced staple retention slots 140 whichare positioned in alignment with the staple forming depressions 122 in atissue contacting surface 142 of the cartridge body 138. Each slot 140is configured to receive a fastener or staple 144 and a pusher 146. Theactuation sled 148 is positioned within the cartridge body 138 to passlongitudinally through the cartridge body 138 into engagement with thepushers 146 to sequentially eject the staples 144 from the cartridgebody 138. For a more detailed discussion of the cartridge assembly 116including the support plate 136, see the '965 publication which has beenincorporated herein by reference

Referring also to FIGS. 3-5, the mounting assembly 112 includes an uppermounting portion 150 and a lower mounting portion 152 which are securedtogether by posts 153 or rivets. Each of the mounting portions 150 and152 includes a pivot member 112 a and 112 b, respectively. As discussedabove, the pivot member 112 a is received within the hole 132 a of thebracket 132 (FIG. 2) of the anvil body 120 to secure the upper mountingportion 150 to the anvil body 120. A first coupling member 156 a (FIG.2) has a first end which defines an opening 158 a which also receivesthe pivot member 112 a and a second end which is received within arecess 113 a defined in the proximal body portion 110 of the replaceablereload 108. The pivot member 112 b is supported on the lower mountingportion 152 and is received in an opening 158 b of a second couplingmember 156 b. The second coupling member 156 b is received within arecess similar to recess 113 a defined in the proximal body portion 152to pivotally secure the lower mounting portion 152 to the proximal bodyportion 110 of the reload 108. The pivot members 139 extend through theopenings 139 a formed in the anvil body 120 and the channel 134 and arereceived in openings 160 (FIG. 3) formed in lower mounting portion 152to secure the lower mounting portion 152 to the channel 134.

Referring again to FIG. 2, the proximal body portion 110 of the reload108 includes an upper housing half 180 and a lower housing half 182which are contained within an outer sleeve 184. When the outer sleeve184 is positioned about the upper and lower housing halves 180 and 182,the first and second coupling members 156 a and 156 b are retainedwithin the recesses 113 a to prevent separation of the tool assembly 106and the proximal body portion 110 of the reload 108. The proximal end ofthe upper housing half 182 and/or lower housing half include engagementnubs 186 for releasably engaging the distal end of the body portion 104of the stapling apparatus 100 in a bayonet-type coupling arrangement.The housing halves 180 and 182 define a channel 190 for slidablyreceiving the drive member 130. An articulation link 192 is dimensionedto be slidably positioned between the upper and the lower housing halves180 and 182 and is adapted to engage an articulation mechanism (notshown) of the surgical stapling apparatus 100. A pair of blow out plateassemblies 196 are positioned adjacent the distal end of the housinghalves 180 and 182 to prevent outward buckling and bulging of the drivemember 130 during articulation and firing of the tool assembly 106stapling apparatus 100. A more detailed discussion of the components ofthe proximal body portion 110 is provided in U.S. Pat. No. 7,143,924 toScirica et al. (“the '924 patent”) which is hereby incorporated byreference herein in its entirety.

Referring also to FIGS. 4-7, the drive member 130 includes a body and aworking end 210 having a knife 212. The working end 210 includes anupper flange 216 a a lower flange 216 b and a vertical strut 214interconnecting the upper flange 216 a and the lower flange 216 b. Theknife 212 is supported on or formed into the vertical strut 214 of theworking end 210. The upper flange 216 a is positioned to be slidablyreceived within the channel 126 (FIG. 6) of the anvil assembly 114 andthe lower flange 126 b is positioned to be slidably positioned along anouter surface 127 of the channel 134. In use, distal movement of thedrive member 130 initially advances the upper flange 216 a into a camsurface 280 a formed on the anvil plate 122 and advances the lowerflange 216 b into engagement with a cam surface 280 b formed on thechannel 134 to pivot the cartridge assembly 116 towards the anvilassembly 114 to a closed or approximated position. Continued advancementof the drive member 130 progressively maintains a minimum tissue gapadjacent the working end 210 as the working end 210 moves through thetool assembly 106.

In certain embodiments, the body of the drive member 130 is formed froma plurality of stacked sheets 130 a-d of material, e.g., stainlesssteel. A locking member 202 is supported about the proximal end of thereload 108 to prevent axial movement of the drive member until thereload 108 is attached to the stapling apparatus 100. A more detaileddiscussion of the above-identified components of the disposable reload108 is described in the '924 patent which has been incorporated hereinby reference in its entirety.

The distal end of the body of the drive member 130 supports the workingend 210 and defines a stop surface 222. The sled 148 is disposed withinthe cartridge assembly 116 at a position distal of the working end 210.When the working end 210 is in its proximal-most position and the toolassembly 106 is in the open or unapproximated position (FIG. 6), thesled and the working end are in their initial position. The sled 148includes a plurality of cam surfaces 228 (FIG. 3) which are positionedto engage the pushers 146 which are positioned within the cartridgeassembly 116 to eject the staples 144 from the cartridge body 136 whenthe sled 148 is advanced through the tool assembly 106. The proximal endof the sled 148 includes one or more fingers 229 which define an opening230 or slot (FIG. 4) which will be discussed in further detail below.

The firing lockout assembly 200 includes a latch member 242 which ispivotally supported on a distal end of the lower mounting portion 152.The latch member 242 includes a U-shaped body (FIG. 4A) having aproximal base member 244 and two spaced distally extending legs 246. Thebase member 244 can be provided with a blocking member 244 a whichdefines a blocking surface and can be welded or secured to the basemember 244 to provide additional support to the base member 244.Alternatively, the proximal end of the base member 244 can define theblocking surface. The latch member 242 is pivotal from a first positionto a second position. In the first position, the blocking member 244 aof the latch member 242 is aligned with the stop surface 222 of thedrive member 130 to prevent advancement of the drive member 130 withinthe tool assembly 106 and in the second position, the blocking member244 a is misaligned with the stop surface 222 of the drive member 130 topermit advancement of the drive member 130 within the tool assembly 106.

Referring to FIGS. 3-6, each leg 246 of the latch member 242 has acentrally located pivot member 250 and an abutment surface 252. Thepivot members 250 are supported on hooked arms 256 of the lower mountingportion 152 of the mounting assembly 112 to pivotally support the latchmember 242 on the lower mounting portion 152. A biasing member ormembers is provided to urge the latch member 242 towards the firstposition. In certain embodiments, the biasing member includes a pair ofsprings 260 which are supported about respective posts 262 affixed to adistal face of the lower mounting portion 152. Each spring 260 ispositioned to engage a respective abutment surface 252 of the latchmember 242 to bias the latch member 242 in a counter-clockwise directionas viewed in FIG. 6. A distal end of each leg 246 includes a downwardlyextending projection 266 which is positioned to extend through theopening 230 defined in the sled 148 when the sled 148 is in a retractedposition, the latch member 242 is in the first position and the anvilassembly 114 and the cartridge assembly 116 are in the approximatedposition (FIG. 7A).

Referring to FIGS. 3 and 4, a spring 290 is disposed about each cylinder292 within the channel 134. Each of the cylinders 292 is affixed to aninner surface of the channel 134 to provide alignment and stability tothe springs 290. Each of the springs 290 is positioned between the innersurface of the channel 134 and a respective blind bore 294 (FIG. 4)defined in a bottom surface of the lower mounting portion 152 to urgethe tool assembly 106 to the unapproximated position. Other biasingmembers or features can be used in place of the springs.

Referring to FIGS. 6 and 7, when the drive member 130 is in the fullyretracted position and the tool assembly 106 is in the unapproximated oropen position, the upper and lower flanges 216 a and 216 b of theworking end 210 of the drive member 130 are spaced proximally of thesled 148 and proximally of cam surfaces 280 a and 280 b formed on theanvil plate 122 and the channel 134, respectively. In the unapproximatedposition of the tool assembly 106, the latch member 242 is urged towardsa counter-clockwise position by springs 260. The lower mounting portion152 includes a surface 298 which is positioned to engage the base member244 or blocking member 244 a. Engagement between the blocking member 244a and the surface 298 of the lower mounting portion 152 prevents furthercounter-clockwise rotation of the latch member 242 to retain the latchmember 242 in the first position.

Referring to FIGS. 7A-7B, when the drive member 130 is advanced distallyby actuating the movable handle 102 b (FIG. 1), the upper and lowerflanges 216 a and 216 b of the working end 210 engage the cam surfaces280 a and 280 b and pivot the cartridge assembly 116 towards the anvilassembly 114 to move the tool assembly 106 to the approximated position.When the tool assembly 106 is in the approximated position, the latchmember 242 remains in the first position such that the downwardlyextending projections 266 of legs 246 of latch member 242 extend throughthe opening 230 of sled 148 and engage the inner surface of the channel134. In the first position, the blocking member 244 a is aligned withbut spaced from the stop surface 222 on the distal end of the body ofthe drive member 130. The working end 210 of the drive member 130 isalso positioned proximally of the major portion of the sled 148.

Referring to FIGS. 8 and 9, when the movable handle 102 a is actuated tofire the stapling apparatus 100 and eject staples 144 from cartridgebody 136 of cartridge assembly 116, the drive member 130 is advanced tomove the working end 210 of the drive member 130 through the toolassembly 106 into engagement with the sled 148 to advance the sled 148distally through the tool assembly 106. As the sled 148 moves distallythrough the tool assembly 106, the proximal fingers 229 of the sled 148,which partially define the opening 230, engage the downwardly extendingprojections 266 of the latch member 242 to pivot the latch member 242about the pivot members 250 of the latch member 242 in a clockwisedirection, as shown in FIG. 9, against the bias of springs 260. As thelatch member 242 pivots in the clockwise direction towards the secondposition, the blocking member 244 a is pivoted downwardly out fromalignment with the stop surface 222.

As viewed in FIGS. 10-11B, continued advancement of the drive member 130effects continued advancement of the sled 148. As the sled 148 isadvanced, the fingers 229 of the actuation sled 148 retain the latchmember 242 in the second position to allow the base 130 a of the drivemember 130 to pass over the blocking member 244 a. The base 130 a of thedrive member 130 retains the latch member 242 in the second positionwith the blocking member 244 a positioned beneath the stop surface 222of the drive member 130.

Referring to FIGS. 12 and 13, when the stapling apparatus 100 has beenfired and the drive member 130 is returned to the retracted position,the actuation sled 148 which was in abutting relationship with the drivemember 130, remains in the distal end of the cartridge body 138. Thelatch member 242 is returned to the first position by the springs 260after the base 130 a of the drive member 130 moves to a positionproximally of the latch member 242. In the retracted position of thedrive member 130, the latch member 242 is returned to the first positionby the biasing springs 260 such that the blocking member 244 a ispositioned in alignment with the stop surface 222 of the drive member130 to prevent readvancement of the drive member 130. Also, the workingend has an angled cam surface facing in a proximal direction, andlocated on the vertical strut, that can urge the latch toward the firstposition.

As illustrated in FIG. 12, with the sled 148 in its advanced position,the fingers 229 of the sled 148 are positioned distally of thedownwardly extending projections 266 of the latch member 242. Thus,readvancement of the drive member 130 does not effect pivoting of thelatch member 242 from the first position to the second position, andreadvancement of the drive member 130 is prevented.

In order to reuse stapling apparatus 100, the drive member 130 must befully retracted and the cartridge assembly must be replaced. Morespecifically, the cartridge assembly is removed from the channel 134 anda new cartridge assembly is positioned within the channel 134. The newcartridge assembly has a sled 148 positioned such that advancement ofthe sled 148 causes fingers 229 again to engage and pivot the latchmember 242 from the first position to the second position, and allowingthe drive member to be advanced.

Persons skilled in the art will understand that the devices and methodsspecifically described herein and illustrated in the accompanyingdrawings are non-limiting exemplary embodiments. It is envisioned thatthe elements and features illustrated or described in connection withone exemplary embodiment may be combined with the elements and featuresof another without departing from the scope of the present disclosure.As well, one skilled in the art will appreciate further features andadvantages of the disclosure based on the above-described embodiments.Accordingly, the disclosure is not to be limited by what has beenparticularly shown and described, except as indicated by the appendedclaims.

1. (canceled)
 2. A lockout assembly configured to prevent a toolassembly from firing, the lockout assembly comprising: a mountingmember; a post disposed parallel to a longitudinal axis of the toolassembly; a biasing member configured to urge the post distally in adirection parallel to the longitudinal axis, the biasing memberpositioned between the post and the mounting member; and a latch memberpivotally supported by the mounting member, the latch member having anabutment surface and a projection, the post engaged with the latchmember to urge the abutment surface of the latch member towards a lockedposition in which the projection is positioned to engage an actuationsled of the tool assembly to prevent advancement of the actuation sled.3. The lockout assembly of claim 2, wherein the mounting member definesa pair of hooks disposed on opposite sides of the longitudinal axis. 4.The lockout assembly of claim 3, wherein the latch member includeslaterally extending wings, each of the laterally extending wingsreceived by one of the pair of hooks to pivotally support the latchmember relative to the mounting member.
 5. The lockout assembly of claim2, wherein the latch member has a first leg and a second leginterconnected by a proximal base member, the first and second legsparallel to and spaced apart from one another on opposite sides of thelongitudinal axis.
 6. The lockout assembly of claim 5, wherein the basemember is configured to engage the mounting member to prevent the latchmember from pivoting beyond the locked position.
 7. The lockout assemblyof claim 2, wherein the post is engaged with the latch member to urgethe abutment surface of the latch member distally such that the latchmember is pivoted towards the locked position.
 8. The lockout assemblyof claim 7, wherein the post is configured to pivot the latch membertowards the locked position such that the projection of the latch memberis pivoted transverse to the longitudinal axis to engage the actuationsled to prevent advancement of the actuation sled.
 9. A lockout assemblycomprising: a mounting member; a biasing member; and a latch memberpivotally supported by the mounting member and including a blockingmember, a pivot member, and a projection, the latch member pivotableabout a pivot axis defined by the pivot member between a locked positionin which the blocking member is in a blocking position and an unlockedposition, the projection positioned distally of the pivot member and theblocking member positioned proximally of the pivot member, the biasingmember urging the latch member towards the locked position, whereinapplication of a force to the projection in a first direction pivots theblocking member in a second opposite direction to move the latch memberfrom the locked position to the unlocked position.
 10. The lockoutassembly of claim 9, further including a post engaged with the latchmember and defining an axis that is orthogonal to the pivot axis,wherein the biasing member urges the post distally to urge the latchmember towards the locked position.
 11. The lockout assembly of claim10, wherein the biasing member is positioned between the post and themounting member.
 12. The lockout assembly of claim 9, wherein themounting member defines hooks, the hooks disposed on opposite sides ofthe latch member along the pivot axis.
 13. The lockout assembly of claim12, wherein the latch member includes a laterally extending wings, eachof the laterally extending wings received by one of the hooks of themounting member to pivotally support the latch member on the mountingmember.
 14. The lockout assembly of claim 9, wherein the latch memberincludes a first leg and a second leg, the first and second legs of thelatch member having proximal portions that are interconnected by a basemember, the first and second legs extending along axes that are parallelto and spaced apart from one another.
 15. The lockout assembly of claim14, wherein the base member is configured to engage the mounting memberto prevent the latch member from pivoting beyond the locked position.16. The lockout assembly of claim 14, wherein the projection includestwo projections and each of the first and second legs includes one ofthe two projections.
 17. The lockout assembly of claim 9, wherein thelatch member includes an abutment surface and the post is engaged withthe abutment surface.
 18. A tool assembly comprising: an anvil assembly;a cartridge assembly coupled to the anvil assembly, the anvil assemblyand cartridge assembly movable between an unapproximated position and anapproximated position; a drive member movable from a retracted positionto an advanced position to move the anvil assembly and the cartridgeassembly from the unapproximated position to the approximated position,the drive member having a stop surface; and a lockout assembly accordingto claim
 9. 19. The tool assembly of claim 18, wherein the cartridgeassembly includes an actuation sled positioned to be engaged by thedrive member as the drive member is moved from the retracted positiontowards the advanced position to move the actuation sled from aretracted position to an advanced position, wherein it its retractedposition, the actuation sled engages the projection of the latch memberto move the latch member from its locked position to its unlockedposition.
 20. The tool assembly of claim 19, wherein the drive memberabuts the actuation sled as the drive member moves from its retractedposition towards its advanced position to move the actuation sled fromits retracted position towards its advanced position.